Question

A bag contain 5 red and 2 green balls. At random a ball is drawn from this pot. If a drawn ball is green then put a red ball in the pot and if a drawn ball is red, then put a green ball in the pot, while drawn ball is not replace in the pot. Now we draw another ball randomnly, the probability of second ball to be red is A. `(27)/(49)` B. `(26)/(49)` C. `(21)/(49)` D. `(32)/(49)` Select the correct answer from above options

Answer 1

Correct Answer - D Let A be the event that ball drawn is given and B be the event that ball drawn is red. ∴ P(A)= 2 7 and P(B)= 5 7 Again, let C be the event that second ball drawn is red. ∴ P(C)=P(A)P(C/A)+P(B)P(C/B) = 2 7 × 6 7 + 5 7 × 4 7 = 12+40 49 = 32 49